Sweet Sisters
by HopeInMyHeart
Summary: Ella Sloan Montgomery has always wanted a baby sister. Now that she has one, it's up to her mom to make sure that they have a  chance to meet one another.   Addison carried hers and Mark's daughter to term, and lives with her in Seattle!
1. Chapter 1

"Ella Sloan Montgomery!" Addison stands in the kitchen of her suburban Seattle house, frustrated that her almost 6 year old daughter is about to miss her school bus. _Again._ She is an anxious wreck this morning, desperate to return to Seattle Grace to check on the status of her friend, Callie Torres, and her unborn baby, Ella's half sister, who had been in a horrific car accident the morning before.

She quickly climbs up the stairs. "Ella, honey, what are you doing?" she pokes her head into her daughter's bedroom, and holds back as a smile.

"Is it time to go?" Ella looks up from her barbies.

Addison raises an eyebrow "Ella. I've been calling you to come downstairs for 10 minutes now, didn't you hear me?"

Ella shakes her head, "I don't even like school anyway. Barbies are more fun."

Addison sits on the edge of the bed. "Can't argue there but, it's time for school little lady. "Shoes please."

Addison finds her patience wearing thinner as Ella slowly works to put on her shoes, adjusting her socks, and repositioning the velcro strap on her mary janes so that they fit just. right.

"Okay mommy. Now I'm ready." Ella gets to her feet and reaches for Addison's hand.

* * *

><p>No sooner has Addison kissed Ella goodbye on the playground, she can hear her phone ring from deep inside her purse. Nervously, she snatches it out of her bag as she makes her way back to her car.<p>

"Addison?" Mark's voice is thick, and she can tell he hasn't slept a wink since the night before.

"Mark what's up, any changes?"

"No, I was just wondering what your ETA was."

"15 minutes." she promises.

She finally makes her way to the ICU at Seattle Grace Mercy West, and steels herself for what could be a very difficult day. Immediately, she runs into Mark, who is watching Arizona speak quietly to Callie while she holds her hand.

"You should go in there. Make peace. You both love Callie." She gently suggests. But Mark brushes off the suggestion.

"Got nothing left to say." he mutters.

Suddenly, an alarm sounds from Callie's room, and moments later, Addison realizes, This could be the moment where Ella's sister is born way too soon. She prays over and over that she is wrong.

"She's got a long, hard fight ahead of her." Addison says quietly, as Arizona and Mark peer into the incubator that night. The baby was 1 pound, 1 oz, born with no heartbeat to speak of. The fact that she had made it even an hour into her life was something of a miracle, in Addison's opinion.

* * *

><p>"She's a 17 week preemie. The next few weeks... It'll be touch and go, but, I'll be here, every step of the way."<p>

Arizona and Mark both quietly nod, well aware of the risks that accompany a micro preemie, and grateful that Addison would be there to watch out for their daughter.

"I'm going to go sit with Callie." Arizona murmurs. She is numb, and still reeling from the fact that she had just saved the life of their daughter that morning.

Mark swallows the lump in his throat as he turns to Addison.

"I need you to be straight with me Addison" He says quietly.

"I am, Mark. Your daughter is stable, but critical. Right now, it's the best we can hope for." She looks at the clock, and sighs deeply. "I need to get home. I promise you, I will be back here first thing tomorrow morning to check on her." Addison hugs him tightly. "Try and get some rest Mark. Your daughters need you." she gently reminds him.

"Tell Ella I love her." he whispers.

"I always do." she squeezes his hand tightly.

* * *

><p>The exhaustion, both physical and emotional hit Addison like a wall as she quietly enters her house.<p>

"Brooke?" She softly calls out for Ella's babysitter.

"Mommy?" Ella appears in the doorway of their living room clutching her stuffed monkey tightly.

"Ella sweetie, you're still awake? It's late, you should be asleep." Addison sets down her bag and kneels down to hug her little girl.

"I missed you mommy. You weren't here when I got home, and not at dinner. Mommy, where were you?"

Brooke appears behind Ella, "I'm sorry Addison, She was just a little nervous about where you were."

"It's okay Brooke. I'll put her to bed. We'll see you tomorrow"

Ella waves as Brooke kisses her forehead, "See you soon okay Bug?" She winks at Ella.

As Brooke quietly closes the front door behind her, Addison lifts her daughter into her arms, unsure if now would be the right time to tell her about her brand new sister. Things were so touch and go, the last thing she wanted was to break Ella's heart if anything should happen to the baby.

"I was actually with your daddy today." She decides.

Ella's face lights up. "Daddy?"

Addison nods and snuggles Ella on the couch. "He wanted to tell you he loves you very, very much Ella."

"Is he still picking me up after school tomorrow?"

Addison hesitates. "Oh, baby he won't be able to, not tomorrow. I'm so sorry"

Ella's face crumples. "But he promised!" She buries her head in Addison's shoulder.

"I know baby girl. I'm sorry. He just... He's super busy, but as soon as he can see you, Ella, I promise, He'll come. He will."

"Why can't he come tomorrow?" Ella sobs.

Addison strokes her hair. "He's... got to work sweetheart." She reasons that lying to her child to protect her was far better than telling her the truth, that he new sister was clinging to life in the NICU.

"I hate work." Ella pouts.

Addison nods. "Me too." and on a night like this, she means it.


	2. Chapter 2

Addison carries Ella up to her room, and gently tucks her daughter into her princess bed.

"Mommy will you stay?" Ella blinks her blue eyes sadly.

"Alright bug." Addison nods, "I'll stay." she stretches out next to her daughter, and rubs her back. It was hard to believe Ella was only a few short weeks away from turning six years old. It had felt like only a minute ago that she had given birth to her back in New York City. She runs her fingers through Ella's fine strawberry blonde hair, and listens to her begin to breath deeper, signaling that she was, indeed, asleep.

Addison makes no motion to leave though. It is equally hard to believe that she had almost gone through with giving up her pregnancy. She shudders to think of her life without Ella now. The sassy, shoe loving, face making goofball of a little girl whose first word was "Cookie." Who worshipped the ground her dad walked on since day one, who loved princesses and super heroes equally, and was on the verge of finally losing her first baby tooth.

Addison remembers the night she decided not to give up the pregnancy. Mark dropped to his knees, weeping with gratitude, and promising to be a good father, despite Addison's concerns. And he had been. Mark Sloan had turned out to be the most wonderful father she had ever known. The night Ella was born, he refused to return back to his apartment to sleep, and took to sleeping in the uncomfortable recliner situated in Addison's room, his hand on Ella's isolette the entire first night.

Their arrangement for raising their daughter was as modern as could be. They had decided, equally, half way through Addison's pregnancy that their relationship as lovers was simply no longer working. However reformed Mark Sloan was, he was still Mark Sloan, and Addison would never want to see her daughter hurt by the pain of watching her parents divorce. The plan was to co parent, sharing the responsibilities 50/50. and it worked for them perfectly, even during the occasional rough patches they faced.

The night before Ella's birthday second birthday party, Addison received an urgent call from her old mentor, Richard Webber in Seattle. He had an extremely intriguing offer, to bring her services as one of the foremost Neonatologists to her own NICU at Seattle Grace, but of course, there was a catch. Seattle Grace was where her ex husband worked. Two years had gone by, they had been amicably divorced, but still. There was a lot more to consider. Mark, for one, would not take kindly to the idea of her moving their child all the way to Seattle.

After the birthday party had ended, and Ella had gone down for a much needed nap that afternoon, Addison and Mark finally got a moment to talk alone.

Mark could immediately see the anxiety on her face. "I need to talk to you." she bit her lip nervously

"What's wrong, is Ella okay? Are you okay?" He removes his party hat and sits down.

"Everything is fine." she started. "I just... I got a job offer last night."

Mark's face relaxed. "That's great! Where? Beth Israel? Mt Sinai? Don't take it if it's Mt. Sinai, I've heard some pretty sketchy things-"

"Mark stop." Addison interrupted. "It's not in New York."

"Okay... where is it Addison?"

Addison hesitated. "Seattle."

Mark laughed, "You're serious? Seattle?"

"Richard Webber called last night. He made me a really amazing offer. They're expanding their NICU. They need a head of Neonatology." she explains.

Mark stared at her. "You're not seriously considering this are you? Seattle? Is this because you're not over Derek or something?"

Addison stared back. "No, Mark. I'm thinking about my career. What's best for my family."

"Oh please!"

"Keep your voice down" Addison hissed, "You'll wake the baby."

Mark stood up, his fists clenched in frustration. "You can't take her to Seattle, Addison."

"Addison looked away from him, "Nothing's been decided yet Mark."

"If you want a fight over this, you'll get one." Mark's voice wavered with emotion, and Addison could feel her heart breaking as he walked out of the apartment angrily.

Later that night, Just as Addison had finally gotten Ella to settle down for bed time, she heard the front door quietly open. She closed the door to Ella's room, and walked into her living room, unsurprised to see Mark standing there quietly.

"I'm sorry." Addison started to say, but Mark shook his head. "I've had all afternoon to go over this."

"Okay"

"I won't lose my family. I won't do it Addison, If you take her to Seattle. I'm going too. I'll find a job out there, I'll do what it takes. I won't lose my daughter." he finally said.

Addison smiles to herself, now knowing that the move to Seattle had been the best thing to ever happen to her and Ella and, as it turned out, Mark. Ella often talked about how much she loved her house, and the jungle gym Daddy had built for her in Mommy's back yard, and most of all, her school. It was clear that their daughter was thriving. Mark had had his ups and downs in the department of love, but had managed to find his own way, and often talked about how happy he was in Seattle, despite his hatred of the rain.

"Mommy?" Ella cries out quietly.

"I'm right here bug." Addison whispers. Ella turns, and wraps her arms around Addison's neck.

"I love you, Mommy." she sleepily says, before snuggling back into a deep sleep, all the while, holding tightly to Addison.


	3. Chapter 3

"How did she do overnight?" Addison asks softly, standing over the baby's incubator early the next morning.

Reese, her nurse exhales slowly. "It was a tough night. She had multiple apnea spells, heart rate was bradycardic for a bit, but, she's still here. She made it through her first night, that's something, right?"

Addison nods quietly. "it is certainly something." she agrees. "alright. I'm off to rounds, but page me, immediately if anything changes."

"Addison?" Mark's voice snags her attention as she is tossing her NICU gown in the trash can.

"Hey."

"How is she this morning?" Mark rubs his eyes, any new news?"

Addison shakes her head. Right now, she's stable, but she had a few apnea spells last night, and some bradycardia that we're keeping an eye on. This is all normal activity in a micro preemie Mark, this is to be expected.

Mark sighs and runs his hands through his hair. "Alright. Okay, thanks for the update. He lightly kisses her cheek. "How's Ella?"

Addison smiles a little. "Ella's good. She was upset when I told her you wouldn't be picking her up today but, she said she loves you, and she'll see you soon."

"Did you tell her, about-"

"No."

Mark nods. "Probably best to wait, right?

"Right."

! She's crashing! Reese's voice is frantic as Addison and Mark both race back over to the incubator.

Addison works quickly to stabilize the baby's slowing heart rate. "Damnit." she mutters.

"What is it, is it another apnea spell?"

"Mark. Outside. Now." Addison orders.

Mark shakes his head. "No."

"Mark I mean it, if you want me to save your kid, I need you to not be standing over me" she insists.

She looks at Reese as she pulls her stethoscope out of her ears. "She's developed a PDA. I was really afraid of this."

* * *

><p>"She's too little for surgery right now." Arizona murmurs quietly.<p>

"Right." Addison nods. "right now, your little girl is stable. But, if the PDA gets worse, I'm afraid there's only so much I can do. She needs to have more strength before I'm comfortable opening her chest."

Arizona nods. "So we should prepare ourselves then, right?" She looks at Mark, who is wiping tears away.

Addison swallows hard. "I wish there was more I could do right now. If there was anything else to do, you know I'd do it."

"Addie. Stop." Arizona grips her hand. "You're the best there is. And if you're telling us that at this point there's nothing we can do, I believe that."

"I don't." Mark says.

"Mark." Addison shakes her head.

"No. you can't just... give up on her. How dare you!" Mark angrily storms away.

Addison leans her head against the NICU door. "He thinks I'm giving up." She shakes her head. "This is my daughter's half sister Arizona. Does he think I want her to die? Does he think I get any kind of... anything by having to tell my 6 year old that she's not going to be a big sister?"

"I know, Addison, I don't think you're giving up on our little girl." Arizona wipes her eyes. "And neither will Callie."

"we need to tell her."

Arizona glances back towards the baby. "We named her,late last night. Mark, and Callie and I." She finally says. Addison can feel the pain in her voice, and understands the hesitation that comes along with the sentence. Naming her, and then losing her, after beginning to give her a real sense of self was terrifying.

"Oh?" Addison smiles. "What did you guys decide?"

Arizona takes a deep breath. "Sofia."

"_Sofia_." Addison breathes. "That's beautiful."

"Sofia Robbin Sloan Torres." Arizona is now smiling proudly, while wiping tears away. She looks away from Addison. "I'm sorry." she whispers.

"Arizona, it's okay."

"I just don't want to lose her."

"I know." Addison hugs her tightly. "None of us do."


End file.
